1. Field
The present device relates to the field of exercise equipment, particularly to an apparatus or device that allows a person who is exercising with dumbbells or a barbell to self-spot him or herself for increased safety and a more effective workout.
2. Prior Art
Athletes of many disciplines, as well as laypeople, improve their strength and endurance by including weight training in their workout regimens. Most people skilled in kinesiology are of the opinion that the lifter will experience superior results when using free weights rather than a cable machine. Free weights provide the lifter with a more natural workout that strengthens all the muscle groups that are used in everyday life. Specifically, free weights strengthen stabilizer muscles in a way than cable machines cannot.
For maximum strength and muscle mass gain, the lifter will perform repetitions until he or she is physically unable to raise the weight again. This is called going to exhaustion. Some exercises, such as a bicep curl, do not result in the barbell or dumbbell substantially being placed above the lifter's body. Therefore, there is no real danger of the lifter dropping the weight on him or herself and a spotter is not needed. In other exercises—such as squats, shoulder presses, and bench presses—the weight is above the lifter's body for the duration of the exercise. There is a high likelihood of the weight falling on the lifter if he or she attempts to go to exhaustion without a spotter present. In the case of elite athletes, the weight being lifted is often heavy enough to seriously injure or even kill the lifter if it is dropped. This is a reason why many people who do not have a workout partner decide to use cable machines instead of cheaper and more effective free weights. Even when a human spotter is present, accidents have occurred where the spotter fails to catch the weight when the lifter drops it.
To address this issue, the exercise industry has developed many solutions. The most widely available mechanical spotting devices are the power rack and the smith machine. A power rack is simply a large rack that the lifter is inside while lifting. A power rack cannot be used with dumbbells. The barbell sticks out the side of the rack and there are adjustable horizontal supports to prevent the bar from falling on the lifter. This is effective from a safety standpoint but leaves a lot to be desired in terms of user-friendliness. In the case of bench pressing, the supports are set to a level that allows the bar to nearly contact the lifter's chest. (In order to gain the most benefit from the workout, the lifter must move through his entire range of motion.) If the lifter reaches the point of complete exhaustion on a set, the barbell will come crashing down to within inches of his or her face. Since this would occur at the end of every set, many people would prefer a better solution.
A smith machine is not quite a free weight experience but is still better from a muscle building perspective than a cable machine. A commercial disadvantage of a smith machine is its high price, due to its size and complexity. It consists of a special barbell mounted in a nearly vertical slide mechanism with hooks attached to the barbell at the same width as the slides. When the lifter begins a set, he lifts and rotates the barbell so that the hooks detach from holes near the slides and the barbell is permitted to slide up and down. At the end of the set, the lifter simply rotates the bar to place the hooks back in their respective holes or notches, holding the barbell in place. The operational disadvantage of this approach is that many stabilizer muscles are not sufficiently stressed, leading to imbalanced muscle growth. A lifter who used only a smith machine in his training will not be able to lift the same weight if he goes to free weights later on. During free weight squats the barbell naturally follows a slightly curved path. The smith machine does not allow for this, resulting in an unnatural workout. Most smith machines are too short to allow for standing shoulder or military presses. The lifter must be seated during these exercises, reducing the benefit of the workout to his core muscles. Due to these disadvantages, many people and companies have attempted to create improved self-spotting devices.
There is a device (U.S. Pat. No. 6,296,648) that works by allowing the lifter to control the height of two horizontal supports while he or she is in the middle of his set. The motors that operate the supports are sufficiently powerful enough to lift the entire weight of the barbell. The advantage to this approach is that the lifter can perform forced reps as well as lift the bar off his or her chest if it turns out that he or she is unable to lift the bar at all after lowering it. Also, this system has nothing attached to the barbell, providing a genuine free weight workout. The disadvantages are that it can only be used for bench pressing with a barbell and is very expensive due to the large electric motors. Also, it requires household AC voltage to operate.
There are various devices that use motor-driven drums mounted in a frame that operate cables, which are attached to a barbell or dumbbells. In some of these, the motor must be activated in order for the cable to extend or retract. This requires tension and speed sensors as well as a logic processor. Examples of such devices are described in U.S. Pat. Nos. 4,949,959 and 5,048,826. In these devices the cables are not independently extendable or retractable, which reduces user-friendliness.
To provide independent travel of the cables, the weightlifting industry developed devices which have a separate motor for each cable. For example, each cable extends and retracts from a drum that is turned by a motor, as shown in U.S. Pat. No. 4,998,721. Although each motor can operate independently, they are under constant low-level actuation to maintain tension on the cables; this once again requires the use of electronic sensors. As with the patents in the previous paragraph, the fixed location of the cables prevents the apparatus from being used for dumbbells or varying lengths of barbells.
In an effort to eliminate the necessity of maintaining an actuated motor during a workout, the weightlifting industry has enlisted the use of motor-clutch assemblies. For example, as shown in U.S. Pat. No. 6,379,287, one end of each cable is attached to an assembly that moves up and down in the frame of the apparatus. This reciprocating component is fixed to an endless chain that turns a rotary pawl clutch on the motor shaft, which is lockable to prevent movement of the cable. The reciprocating component also has a counterweight that provides tension on the cable, relieving the motor of this function. The distance between the two cables is adjustable to allow for the use of dumbbells and varying lengths of barbells. A disadvantage of this design is that the spotting apparatus is not compact and modular. The entire machine must be assembled by the producer and shipped as a single unit. Also, the apparatus cannot be easily integrated into existing exercise equipment, requiring a large capital investment by the manufacturer in creating a dedicated production line. These factors contribute to the high retail price and low regional availability of such a product.
A person skilled in the art may realize that a motor drive is not strictly necessary for a cable-based self-spotting device. The main function of the machine is to prevent the weight from falling on the lifter. Therefore, it is sufficient to have a system that simply provides tension on the cable during the set and then holds the weight in place after the lifter reaches the point of exhaustion. This is the reasoning behind U.S. Pat. No. 6,893,381. It is similar to No. 6379287 mentioned earlier, in that it has a cable attached to a reciprocating drive that turns an endless chain. It does not, however, have a rotary pawl clutch on the motor. It instead uses pawls that fit into the links of the chain. When the lifter closes the barbell-mounted switch, a solenoid retracts the pawl from the chain. When the lifter releases the switch, the pawl is re-engaged through spring pressure. Thus the mechanism that arrests the downward motion of the weight is independent of the motor. If power-raising of the weight is desired, the lifter can control the motor separately. The consumer and the manufacturer can choose whether to spend money on a power-raising feature. However, the shortcomings of this apparatus are identical to those of U.S. Pat. No. 6,379,287. It is not compact, modular, nor inexpensive to produce.
In light of these attempts at creating a self-spotting machine that works better than a power rack or a smith machine while being commercially viable, there remains a need for a self-spotter that is compact, modular, and inexpensive to produce.